Issue link: http://read.dmtmag.com/i/34501
RUNOUT AND VIBRATION DIAGNOSIS Rotating assembly runout can influence vehicle vibration and contribute to irregular tire wear. Following these procedures for verifying the concentricity of the guide rib area as well as ensuring that both radial and lateral runout measurements are the lowest possible will aid in reducing any tire/wheel/hub assembly contribution. If the value is between 0.001" and 0.060", continue with procedures below. If the value is >0.060", remove and deflate the tire, break it loose from the rim, lubricate, rotate the tire 180 degrees, reinflate, and recheck runout. Radial Runout Tools needed: • Tire runout gauge (or dial indicator) • Air pressure gauge • Tread depth gauge • Feeler gauge • Six inch metal ruler • Tire marking crayon • Jack and jack stands The first step is to eliminate possible sources of the disturbance (operation conditions, alignment posture, driveline component balance and angles, frame and chassis concerns, fifth wheel placement, and possible excessive stacked tolerances). Find out as much as you can that may be related to the issue to aid in the initial diagnosis (maintenance file, test drive, driver interview). Examine the assemblies for proper air pressure, proper mounting, verify balance if balanced, inspect for tire and or wheel/rim damage. Verify torque and proper component assembly on tube-type or multi-piece assemblies. Proper mounting procedure will reduce runout where it starts during the mounting process. Jack up the front end of the vehicle so axle is unloaded and place jack stands for support. Inspect front end components, including wheel bearing and kingpin play, suspension and rear assemblies. Use the tire runout gauge to check for both radial (top photo) and lateral runout (bottom photo) for the rotating assembly. Values over 0.060 inch will be a detectable cause of vibration in steer assemblies and on recreational vehicles. Current TMC (Technology & Maintenance Council) assembly tolerances are 0.095 inches, radial and lateral (See Balance and Runout, Page 42). 134 Section Nine: Appendix Measuring Radial Runout on Center Rib Measuring Lateral Runout on Outside Shoulder Incorrect bead seating can occur on one or both bead seats. This usually results in a high radial and/or lateral reading. General cause is improper mounting procedures or wheel/rim is at tolerance limits. It may require taking 3 radial readings to detect: outside shoulder, center rib, and inside shoulder. Incorrect Bead Seating